Retrograde degeneration of neural fibers following a focal infarct in the brain and its impact on functional recovery

Objective To investigate the retrograde degeneration following a recently focal infarct as well as its potential impact on neurological recovery.Methods 16 patients with a cerebral infraction at unilateral posterior limb of internal capsule or at brainstem underwent DTI and evaluation with the NIH Stroke Scale(NIHSS),the Fugl-Meyer motor scale(FM) and the barthel index(BI) 3 times at the first week(W1),the fourth(W4) and twelfth week(W12) after stroke onset respectively.Sixteen gender and age match healthy volunteers underwent DTI one time.Mean diffusivity(MD) and fractional anisotropy(FA value) were measured at centrum semiovale and initial lesion(posterior limb of internal capsule,cerebral peduncle or pons).Spearman correlation analysis was used to assess the association between the absolute value of percent change [((W12-W1) /W1) × 100%] of FA values and of clinical scores.Results Compared to the controls,the FA values of centrum semiovale in patients significantly decreased at every time point(patient group:W1:0.43±0.02,W4:0.39±0.01,W12:0.33±0.02,vs control group:0.46±0.01,P0.01).In patients group,the FA values of centrum semiovale decreased progressively from W1 to W12(P0.01),but no significant modification of MD was observed.The absolute value of percent reduction of FA value of centrum semiovale in patients associated negatively with the absolute value of percent change of NIHSS and FM,but not with the absolute value of percent change of BI(P0.05).Conclusions A subcortical infarct may result the retrograde degeneration in proximal portion of the fiber pathway through the primary lesion.The retrograde degeneration will exist and progress at lest three months,which may hamper the process of neurological recovery.